Gate valve for semiconductor processing system

ABSTRACT

A gate valve ( 20 ) for a semiconductor processing system includes a base frame ( 28 ) configured movable along a guide ( 26 ) to move toward and away from a valve seat ( 22 ), which surrounds an opening portion ( 14 ). A first stopper ( 56 ) is disposed at the upper end of the guide ( 26 ), for defining the movement limit of the base frame ( 28 ) on the valve seat ( 22 ) side. A swing frame ( 34 ) is rotatably attached to the base frame ( 28 ), and has an upper end connected to a valve plug ( 24 ). The swing frame ( 34 ) is connected to the base frame ( 28 ) by a link mechanism ( 36 ), which can bend and stretch while flexing an intermediate portion, and by a spring and damper member ( 46 ). The intermediate portion of the link mechanism ( 36 ) has a mediation member ( 38 ) connected to a reciprocation rod ( 54 ) of an air actuator ( 52 ).

TECHNICAL FIELD

The present invention relates to a gate valve used on, e.g., a load lockchamber or a process chamber in a semiconductor processing system forsubjecting a target substrate, such as a semiconductor wafer, to aprocess. The term “semiconductor process” used herein includes variouskinds of processes which are performed to manufacture a semiconductordevice or a structure having wiring layers, electrodes, and the like tobe connected to a semiconductor device, on a target substrate, such as asemiconductor wafer or an LCD substrate, by forming semiconductorlayers, insulating layers, and conductive layers in predeterminedpatterns on the target substrate.

BACKGROUND ART

Conventionally, a structure utilizing a link mechanism or a cammechanism is known as a driving mechanism for a gate valve. For example,Jpn. Pat. Appln. KOKAI Publication No. 5-196450 discloses a gate valveemploying a link mechanism, as shown in FIG. 10. Jpn. Pat. Appln. KOKAIPublication No. 10-159999 discloses a gate valve employing a cammechanism, as shown in FIGS. 11A and 11B.

The gate valve 100 shown in FIG. 10 is disposed between a load lockchamber 110 and a process chamber 120. The gate valve 100 includes abase body 102 and a valve plug 105 disposed in a gate casing 106. Thebase body 102 is connected to an actuator 101. A guide rail 107 isdisposed on the wall of the gate casing 106 on the load lock chamber 110side, so that the base body 102 is guided to move up and down. The valveplug 105 is connected to the base body 102 by links 103 and 104 at upperand lower positions. The valve plug 105 is further connected to the basebody 102 by a spring 108. The valve plug 105 opens and closes an openingportion 121 of a process chamber 120.

When the opening portion 121 of the process chamber 120 is closed, theactuator 101 is activated to integratedly move up the base body 102 andthe valve plug 105 along the guide rail 107. Even after a roller 109disposed at the top of the valve plug 105 comes into contact with theceiling of the gate casing 106, the base body 102 keeps moving up.Consequently, the valve plug 105 cannot move up any more, but movestoward the opening portion 121 of the process chamber 120 against theaction of the spring 108 while rotating the roller 109. When the basebody 102 reaches the upper end, the height of the base body 102 isleveled with that of the valve plug 105. At this time, the valve plug105 is strongly pushed against the opening portion 121 of the processchamber 120 by the links 103 and 104, so that the opening portion 121 isclosed.

When the opening portion 121 is opened, the actuator 101 is activated inthe opposite direction to move down the base body 102. Consequently, thevalve plug 105 is pulled by the spring 108 toward the base body 102, sothat the opening portion 121 is opened. Then, the base body 102 movesdown further, and the valve plug 105 returns to the initial state by theaction of the spring 108.

The gate valve 100 shown in FIG. 10, i.e., disclosed in Jpn. Pat. Appln.KOKAI Publication No. 5-196450, employs members, such as the guide rail107 and the spring 108, other than the link mechanism, at positions nearthe valve plug 105, to realize a sliding movement of the base body 102and the valve plug 105, and their movement to/from the opening portion.As a result, this structure entails a problem in that the roller 109comes into contact with the inner wall of the gate casing 106, therebymost likely generating particles.

On the other hand, the gate valve 200 shown in FIGS. 11A and 11Bincludes a valve plug 201 for opening and closing an opening portion210. A pair of right and left side plates 202 are fixed to the valveplug 201 at each of the upper and lower levels. Each of the side plates202 is provide with a first guide groove 203 formed therein and having aunique shape.

The gate valve 200 also includes valve plug driving rods 205, which areprovided with second guide grooves 204 formed therein and each having aunique shape corresponding to the first guide groove 203. The valve plugdriving rods 205 are connected to the valve plug 201 by shaft rollers206 each inserted in the first and second guide grooves 203 and 204. Thevalve driving rods 205 are further connected to the side plates 202 bysprings 207.

FIG. 11B is an enlarged view showing the relationship between the firstand second guide grooves 203 and 204, and the roller 206. As shown inFIG. 11B, when the opening portion 210 is in an open state, the guidegrooves 203 and 204 are displaced from each other, viewed from a lateralside.

When the opening portion 210 is closed, the valve plug driving rods 205are activated to move down the valve plug 201 with a gap interposedbetween the valve plug 201 and the valve seat 211. The valve plug 201comes into contact with a stopper 212 below the opening portion 210, butthe valve plug driving rods 205 move down further against the action ofthe springs 207. Consequently, the rollers 206 slightly shift the sideplates 202 through the first guide grooves 203 toward the openingportion 210, and finally push the valve plug 201 against the valve seat211.

When the opening portion 210 is opened, the valve plug driving rods 205move up. At this time, the rollers 206 move up in the respective firstguide grooves 203 by the springs 207 to separate the valve plug 201 fromthe valve seat 212. Then, the valve plug driving rods 205 further moveup, so that the valve plug 201 moves up with the gap kept between thevalve plug 201 and the opening portion 210 to return the initial state,while the rollers 206 maintain the state shown in FIG. 11B.

The gate valve 200 shown FIGS. 11A and 11B, i.e., disclosed in Jpn. Pat.Appln. KOKAI Publication No. 10-159999, employs the first and secondguide grooves 203 and 204 to realize the up/down movement of the valveplug 201, and its movement to/from the opening portion. As a result,this structure requires the guide grooves to be worked with highaccuracy, and also entails a problem in that particles are easilygenerated near the valve plug 201 and the opening portion 210.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a gate valve for asemiconductor processing system, which hardly generates particles near avalve seat (opening portion) and a valve plug.

According to a first aspect of the present invention, there is provideda gate valve for a semiconductor processing system, comprising:

a base frame configured movable in a first direction to move toward andaway from a valve seat, which surrounds an opening portion and has afirst seal surface facing a first reference plane;

a first stopper configured to define a movement limit of the base frameon the valve seat side;

a swing frame attached to the base frame, and configured rotatable on asecond reference plane perpendicular to the first reference plane;

a valve plug attached to the swing frame, and having a second sealsurface to engage with the first seal surface thereby to close theopening portion;

a link mechanism connecting the swing frame to the base frame, andconfigured to bend and stretch while flexing an intermediate portion;

a driving mechanism connected to the intermediate portion, andconfigured to move the intermediate portion in the first direction; and

a biasing member configured to apply a resistant force against rotationof the swing frame relative to the base frame,

wherein, it is preset that, when the opening portion is closed, theintermediate portion is moved by the driving mechanism toward the valveseat to first cause the base frame to move until the base frame comesinto contact with the first stopper, and then cause the link mechanismto bend or stretch thereby to rotate the swing frame, such that thevalve plug seats itself on the valve seat, and the first and second sealsurfaces engage with each other.

In a second aspect, there is provided an apparatus according to thefirst aspect, further comprising a guide fixed relative to the valveseat, wherein the base frame moves along the guide.

In a third aspect, there is provided an apparatus according to the firstaspect, further comprising a damper disposed between the base frame andthe swing frame to absorb an impact caused when the swing frame rotatesrelative to the base frame by an action of the biasing member.

In a fourth aspect, there is provided an apparatus according to thefirst aspect, wherein the driving mechanism comprises a reciprocationrod connected to the intermediate portion.

In a fifth aspect, there is provided an apparatus according to thefourth aspect, wherein the reciprocation rod penetrates a slit holeformed in the intermediate portion, and the reciprocation rod is movablerelative to the intermediate portion in a range allowed by the slithole.

In a sixth aspect, there is provided an apparatus according to thefourth aspect, wherein the reciprocation rod is connected to theintermediate portion by a position adjusting mechanism, such that aconnecting position of the reciprocation rod relative to theintermediate portion is adjustable by the position adjusting mechanism.

In a seventh aspect, there is provided an apparatus according to thefourth aspect, wherein one end limit of a stroke of the reciprocationrod is set to correspond to a bend-and-stretch state of the linkmechanism formed when the valve plug seats itself on the valve seat.

In an eighth aspect, there is provided an apparatus according to thefirst aspect, further comprising a second stopper configured to define amovement limit of the intermediate portion on the valve seat side tocorrespond to a bend-and-stretch state of the link mechanism formed whenthe valve plug seats itself on the valve seat.

In a ninth aspect, there is provided an apparatus according to theeighth aspect, wherein the second stopper is fixed to the base frame.

In a tenth aspect, there is provided an apparatus according to the firstaspect, wherein the biasing member connects the swing frame to the baseframe.

In an eleventh aspect, there is provided an apparatus according to thefirst aspect, wherein the link mechanism comprises first and secondlevers connected to the base frame and the swing frame, respectively, tobe pivotable on the second reference plane, and the intermediate portionconnects the first and second levers to be pivotalbe to each other onthe second reference plane.

In a twelfth aspect, there is provided an apparatus according to thefirst aspect, wherein the first direction is substantially parallel tothe first reference plane.

In a thirteenth aspect, there is provided an apparatus according to thefirst aspect, wherein the valve plug and the link mechanism areconnected to the swing frame at first and second positions,respectively, sandwiching a position at which the swing frame isattached to the base frame.

In a fourteenth aspect, there is provided an apparatus according to thefirst aspect, wherein the opening portion is formed in a sidewall of anairtight chamber, in which a target substrate is accommodated, and theopening portion is formed to allow the target substrate to passtherethrough.

In a fifteenth aspect, there is provided an apparatus according to thefourteenth aspect, wherein the valve seat and the valve plug arearranged to isolate a vacuum atmosphere inside the airtight chamber froman atmospheric environment outside the airtight chamber.

According to a sixteenth aspect of the present invention, there isprovided a gate valve for a semiconductor processing system, comprising:

a base frame configured movable in a first direction to move toward andaway from a valve seat, which surrounds an opening portion and has afirst seal surface facing a first reference plane;

a first stopper configured to define a movement limit of the base frameon the valve seat side;

a swing frame attached to the base frame, and configured rotatable on asecond reference plane perpendicular to the first reference plane;

a valve plug attached to the swing frame, and having a second sealsurface to engage with the first seal surface thereby to close theopening portion;

a link mechanism connecting the swing frame to the base frame, andconfigured to bend and stretch while flexing an intermediate portion,the link mechanism comprising first and second levers connected to thebase frame and the swing frame, respectively, to be pivotable on thesecond reference plane, the intermediate portion connecting the firstand second levers to be pivotalbe to each other on the second referenceplane;

a driving mechanism comprising a reciprocation rod connected to theintermediate portion, and configured to move the intermediate portion inthe first direction; and

a biasing member connecting the swing frame to the base frame, andconfigured to apply a resistant force against rotation of the swingframe relative to the base frame,

wherein, it is preset that, when the opening portion is closed, theintermediate portion is moved by the driving mechanism toward the valveseat to first cause the base frame to move until the base frame comesinto contact with the first stopper, and then cause the link mechanismto bend or stretch thereby to rotate the swing frame, such that thevalve plug seats itself on the valve seat, and the first and second sealsurfaces engage with each other.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a first embodiment of the present invention;

FIG. 2 is a perspective view showing the internal structure of the gatevalve according to the first embodiment viewed from above, in a statewhere an opening portion is open;

FIG. 3 is a perspective view showing the internal structure shown inFIG. 2 viewed from below, in the state shown in FIG. 2;

FIG. 4 is a perspective view showing the internal structure shown inFIG. 2 viewed from above, in a state where the opening portion isclosed;

FIG. 5 is a perspective view showing the internal structure shown inFIG. 2 viewed from below, in the state shown in FIG. 4;

FIGS. 6A to 6C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a second embodiment of the present invention;

FIGS. 7A and 7B are a plan view and a sectional front view,respectively, schematically showing the relationship between thereciprocation rod of an air actuator and the mediation member of a linkmechanism, in the gate valve according to the second embodiment;

FIGS. 8A to 8C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a third embodiment of the present invention;

FIGS. 9A to 9C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a fourth embodiment of the present invention;

FIG. 10 is a sectional view schematically showing the structure of aconventional gate valve; and

FIGS. 11A and 11B are views schematically showing the structure ofanother conventional gate valve.

BEST MODE FOR CARRYING OUT OF THE INVENTION

The embodiments of the present invention will be described hereinafterwith reference to the accompanying drawings. In the followingdescription, the constituent elements having substantially the samefunction and arrangement are denoted by the same reference symbols, anda repetitive description will be made only when necessary.

FIGS. 1A to 1C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a first embodiment of the present invention. FIGS. 2 and 3are perspective views showing the internal structure of the gate valveaccording to the first embodiment, viewed from above and from below,respectively, in a state where an opening portion is open. FIGS. 4 and 5are perspective views showing the internal structure shown in FIG. 2,viewed from above and from below, respectively, in a state where theopening portion is closed.

In this embodiment, a gate valve 20 is disposed adjacent to an openingportion 14, which is formed in the sidewall of an airtight load lockchamber 12, for example. The load lock chamber 12 is connected to aprocess chamber on the side reverse to the opening portion 14, in a filmformation apparatus, an etching apparatus, or the like. Typically, theopening portion 14 is used for allowing a target substrate W, such as asemiconductor wafer, an LCD substrate, or the like, to passtherethrough.

The side wall of the load lock chamber 12 is provided with a valve seat22 disposed thereon, which surrounds the opening portion 14, toairtightly close and open the opening portion 14 in cooperation with avalve plug 24 described later. In other words, the valve plug 24 and thevalve seat 22 are arranged to isolate a vacuum atmosphere inside theload lock chamber 12 from the atmospheric environment outside the loadlock chamber 12. The valve seat 22 has a first seal surface 22 a, whichis vertical and arranged to engage with the valve plug 24. In order toclarify the structure of the gate valve 20, it is assumed that the firstseal surface 22 a is arranged opposite to and parallel to a firstreference plane RP1 (see FIG. 2), which is vertical.

A casing 16 is detachably fixed to the load lock chamber 12 below theopening portion 14, for accommodating main parts of the gate valve 20.Although FIGS. 2 to 5 show only part of the casing 16 to expose theinternal structure of the gate valve 20, the casing 16 is actuallyarranged to cover the internal structure. The sidewall of the casing 16on the load lock chamber 12 side (the left side in FIGS. 1A to 1C) isprovided with a guide 26 disposed thereon, which extends verticallydownward in parallel to the first reference plane RP1. In other words,the guide 26 is fixed relative to the valve seat 22.

The base frame 28 is attached to the guide 26 to move vertically alongthe guide 26, so that it can move toward and away from the valve seat22. The base frame 28 has a pair of arms 32 at the upper end, whichextend horizontally toward the side reverse to the load lock chamber 12,and have distal ends pivotally supporting a swing frame 34. Morespecifically, the swing frame 34 is attached to the base frame 28 bymeans of, e.g., pin connection to be rotatable on a second referenceplane RP2 (see FIG. 2), which is vertical and perpendicular to the firstreference plane RP1

The swing frame 34 penetrates an opening portion 17 formed in the casing16, and extends upward to its upper end to which the valve plug 24 isattached. The valve plug 24 has a second seal surface 24 a to engagewith the first seal surface 22 a of the valve seat 22, so as to closethe opening portion 14. The seal surface 24 a of the valve plug 24 isprovided with an O-ring 24 b for airtightly sealing the opening portion14.

The swing frame 34 is connected to the base frame 28 at the lower end bya pair of link mechanisms 36. Each of the link mechanisms 36 can bendand stretch while flexing an intermediate portion. More specifically,each of the link mechanisms 36 includes first and second levers 42 and44, which are connected to the base frame 28 and the swing frame 34,respectively, by means of, e.g., pin connection, so that they arepivotable on the second reference plane RP2. The first and second levers42 and 44 are connected to each other by means of, e.g., pin connection,so that they are pivotable relative to each other on the secondreference plane RP2, using a mediation member 38 for forming theintermediate portions at which the respective link mechanisms 36 canbend.

The swing frame 34 is also connected to the base frame 28 by a springand damper member 46 between the arms 32 of the base frame 28 and thelink mechanisms 36. On the one hand, the member 46 functions as atension spring (biasing member) for applying a resistant force againstrotation of the swing frame 34 relative to the base frame 28. On theother hand, the member 46 functions as a damper for absorbing an impactcaused when the swing frame 34 rotates relative to the base frame 28 bythe action of the tension spring of the member 46.

An air actuator 52 is fixed to the casing 16 between the base frame 28and the swing frame 34, and functions as a driving mechanism for drivingthe valve plug 24. The air actuator 52 has a rod 54, which extendsdownward and vertically reciprocates in the space between the base frame28 and the swing frame 34. The lower end of the rod 54 is connected tothe mediation member 38 of the link mechanisms 36 by means of, e.g.,screw and nut connection.

A pair of first stoppers 56 are disposed at the upper end of the guide26, for defining the movement limit of the base frame 28 along the guide26 on the valve seat 22 side. A pair of the second stoppers 58 aredisposed on the base frame 28 slightly above the link mechanism 36, fordefining the movement limit of the mediation member 38 on the valve seat22 side.

An explanation will be given of an operation of the gate valve 20. Thefollowing drive of the air actuator 52 is performed under the control ofa controller (not shown).

As shown in FIG. 1A, when the opening portion 14 of the load lockchamber 14 is opened, the rod 54 of the air actuator 52 is extended themost. Accordingly, the base frame 28 is positioned at the lower end ofthe guide 26, and the link mechanisms 36 bend the most in the operationrange. As a result, the swing frame 34 is not in a vertical state, butin a state where it has slightly rotated clockwise about the axial pointat the distal ends of the arms 32, and inclines in the casing 16.

Then, when the opening portion 14 is closed, the rod 54 of the airactuator 52 is withdrawn, and the mediation member 38 of the linkmechanisms 36 is pulled toward the valve seat 22. At this time, sincethe spring and damper member 46 applies a resistant force againstrotational movement of the swing frame 34 relative to the base frame 28,thereby not allowing the link mechanisms 36 to stretch (not allowing theinterior angle θ between the first and second levers 42 and 44 to belarger), the base frame 28 begins to move upward along the guide 26 atfirst. The base frame 28 keeps moving upward along the guide 26 untilthe base frame 28 comes into contact with the first stoppers 56, asshown in FIG. 1B. It is preset that, when the base frame 28 comes intocontact with the first stoppers 56, the valve plug 24 exactly comes to aposition facing the valve seat 22 with a small gap therebetween.

Even after the base frame 28 comes into contact with the first stoppers56, the rod 54 of the air actuator 52 is further withdrawn, so that themediation member 38 is pulled toward the valve seat 22 while the baseframe 28 being stopped. Consequently, the link mechanisms 36 stretch(the interior angle θ between the first and second levers 42 and 44becomes larger), the swing frame 34 rotates counterclockwise about theaxial point at the distal ends of the arms 32. As a result, as shown inFIG. 1C, the valve plug 24 moves toward the valve seat 22 and seatsitself on the valve seat 22, so that the first and second seal surfaces22 a and 24 a engage with each other to close the opening portion 14.

Simply put, the movement of the gate valve 20 to close the openingportion 14 is formed of two stages. In the first stage, the base frame28 and the swing frame 34 as a whole move upward by withdrawal of therod 54, until the base frame 28 stops at the first stoppers 56. In thesecond stage, after the base frame 28 stops, only the mediation member38 moves upward by withdrawal of the rod 54, until the mediation member38 stops at the second stoppers 58.

In the second stage, as the mediation member 38 moves upward and thelink mechanism 36 stretches, the valve plug 24 moves forward by theswing frame 34 to close the opening portion 14 at the upper end of itsupward movement, as shown in FIGS. 1C and 4. Accordingly, it is presetthat a bend-and-stretch state of the link mechanisms 36 formed when thevalve plug 24 seats itself on the valve seat 22 accords with themovement limit of the mediation member 38 of the link mechanisms 36 onthe valve seat 22 side, which is defined by the second stoppers 58.

On the other hand, when the opening portion 14 is opened, the gate valve20 is operated in two stages through a sequence reverse to thatdescribed above. Specifically, as the rod 54 is extended, the linkmechanisms 36 are first bent by the action of the spring and dampermember 46. Consequently, the valve plug 24 moves backward by the swingframe 34 to separate from the opening portion 14 at the upper end of itsupward movement, as shown in FIG. 1B. At this time, the base frame 28maintains a state where it stops at the first stoppers 56. Then, the rod54 is extended, and the base frame 28 and the swing frame 34 as a wholemove downward to completely open the opening portion 14, as shown inFIGS. 1A and 2.

In the gate valve 20 according to the first embodiment, the valve plug24 is isolated from and far from the driving section, and does not comeinto contact with any portion other than the valve seat 22. As a result,particles are prevented from being generated near the valve seat 22 andthe valve plug 24, so that the interior of the load lock chamber 12 isunlikely to be contaminated with particles. A fan (not shown) isdisposed under the casing 16, so that air flowing into the casing 16through the opening portion 17 on the upper side is forced to flowdownward from the casing 16. Consequently, particles generated in thedriving section are prevented from flowing toward the valve seat 22 andthe valve plug 24.

FIGS. 6A to 6C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a second embodiment of the present invention. The gatevalve 70 according to this embodiment has an arrangement substantiallythe same as that of the gate valve 20 according to the first embodimentin relation to the main components, but differs in several respects.

Specifically, the gate valve 70 according to this embodiment employs nosecond stoppers 58 for defining the movement limit of a mediation member38 of link mechanisms 36 on a valve seat 22 side. Instead, one end limitof the stroke of the reciprocation rod 54 of an air actuator 52 is setto correspond to a bend-and-stretch state of the link mechanisms 36formed when a valve plug 24 seats itself on the valve seat 22. In otherwords, it is preset that, when the rod 54 is withdrawn the most, thevalve plug 24 exactly seats itself on the valve seat 22.

Furthermore, as shown in FIG. 7A, the mediation member 38 of the linkmechanisms 36 is provided with a slit hole 72 formed therein, which islong in a direction parallel to the second reference plane RP2 (see FIG.2), (i.e., in a direction in which the link mechanisms 36 bend andstretch), and the distal end of the rod 54 penetrates the slit hole 72.As shown in FIG. 7B, the distal end of the rod 54 penetrating the slithole 72 is provided with a male screw portion 74 over a sufficientlength.

A sleeve nut 75 having a sleeve portion 75 a and a flange portion 75 bis screwed onto the male screw portion 74 from above the mediationmember 38. A through-nut 76 having an outer diameter larger than thewidth of the slit hole 72 is also screwed onto the male screw portion 74from below the mediation member 38. The sleeve portion 75 a penetratesthe slit hole 72, and the lower nut 76 is screwed on the male screwportion 74 until it comes into contact with the sleeve portion 75 a. Itis preset that a small gap is formed between each of the sleeve portion75 a, the flange portion 75 b and the nut 76, and the correspondingportion of the mediation member 38. Accordingly, the rod 54 can movealong with the sleeve nut 75 and the through-nut 76 in the slit hole 72.

With this arrangement, the rod 54 and the mediation member 38 can movesubstantially integratedly in the longitudinal direction of the rod 54,while they can move relative to each other on the second reference planeRP2 (in the bend-and-stretch direction of the link mechanism 36) in arange allowed by the slit hole 72. When the valve is being opened andclosed, the position of the mediation member 38 slightly shifts in adirection along the slit hole 72 by the bend-and-stretch movement of thelink mechanism 36. Accordingly, where the slit hole 72 is formed, alateral load applied to the rod 54 due to the bend-and-stretch movementof the link mechanism 36 is relaxed.

The male screw portion 74 at the distal end of the rod 54, the sleevenut 75, and the through-nut 76 function as a position adjustingmechanism. Specifically, the connecting position of the rod 54 to themediation member 38 can be adjusted by this position adjustingmechanism. Even where the stroke of the reciprocation rod 54 of the airactuator 52 is fixed, the stroke length of the rod 54 can besubstantially adjusted by the position adjusting mechanism. Accordingly,one end limit of the stroke of the reciprocation rod 54 of the airactuator 52 can be easily set to correspond to a bend-and-stretch stateof the link mechanisms 36 formed when a valve plug 24 seats itself onthe valve seat 22.

Furthermore, in the gate valve 70, a tension spring 47 and a damper 48are separately disposed, in place of the spring and damper member 46described above. The spring 47 is directly connected to the base frame28 and the swing frame 34 at opposite ends. The damper 48 has a urethanebump 48 a attached to the base frame 28, and a pin 48 b attached to theswing frame 34 at a position corresponding to the urethane bump 48 a.The damper 48 defines the bend limit of the link mechanisms 36, and alsoabsorbs an impact caused when the link mechanisms 36 bend and the swingframe 34 rotates.

The operation principle of the gate valve 70 is basically the same asthat of the gate valve 20. Accordingly, also in the gate valve 70, thevalve plug 24 is isolated from and far from the driving section, anddoes not come into contact with any portion other than the valve seat22. As a result, particles are prevented from being generated near thevalve seat 22 and the valve plug 24, so that the interior of a load lockchamber 12 is unlikely to be contaminated with particles.

FIGS. 8A to 8C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a third embodiment of the present invention. The gate valve80 according to this embodiment has an arrangement in which thedisposition of a base frame 28 and a swing frame 34, the orientation ofan air actuator 52, and so forth are set reverse to those of the gatevalve 20 according to the first embodiment.

More specifically, in the gate valve 80 according to this embodiment,the sidewall of a casing 16 on a side reverse to a load lock chamber 12side (the right side in FIGS. 8A to 8C) is provided with a guide 26disposed thereon, which extends vertically downward. A base frame 28 isattached to the guide 26 to move vertically along the guide 26. The baseframe 28 has a pair of arms 32 at the lower end, which extendhorizontally toward the load lock chamber 12, and have distal endspivotally supporting a swing frame 34.

The valve plug 24 is attached to the upper end of the swing frame 34.The swing frame 34 is connected to the base frame 28 near the upper endby a pair of link mechanisms 36. Each of the link mechanisms 36 can bendand stretch while flexing an intermediate portion. More specifically,each of the link mechanisms 36 includes first and second levers 42 and44, which are pivotally connected to the base frame 28 and the swingframe 34, respectively. The first and second levers 42 and 44 arepivotally connected to each other by a mediation member 38.

The swing frame 34 is also connected to the base frame 28 by a springand damper member 46 near the upper end. An air actuator 52 is fixed tothe casing 16 between the base frame 28 and the swing frame 34. The airactuator 52 has a rod 54, which extends upward and verticallyreciprocates in the space between the base frame 28 and the swing frame34. The upper end of the rod 54 is connected to the mediation member 38of the link mechanisms 36.

A pair of first stoppers 56 are disposed at the upper end of the guide26, for defining the movement limit of the base frame 28 along the guide26 on the valve seat 22 side. The movement limit of the mediation member38 on the valve seat 22 side is defined by one end limit of the strokeof the reciprocation rod 54 of the air actuator 52.

In the gate valve 80, the swing frame 34 rotates about its lower end.Accordingly, even where the rotation angle of the swing frame 34 isequal to that of the gate valve 20 according to the first embodiment,the valve plug 24 can move back and forth with a larger distance. Alsoin the gate valve 80, when the rod 54 of the air actuator 52 iswithdrawn the most, the opening portion 14 is opened (see FIG. 8A), andwhen the rod 54 of the air actuator 52 is extended the most, the openingportion 14 is closed (see FIG. 8C).

Although there are several differences other than the matters describedabove, the operation principle of the gate valve 80 is basically thesame as that of the gate valve 20. Accordingly, also in the gate valve80, the valve plug 24 is isolated from and far from the driving section,and does not come into contact with any portion other than the valveseat 22. As a result, particles are prevented from being generated nearthe valve seat 22 and the valve plug 24, so that the interior of a loadlock chamber 12 is unlikely to be contaminated with particles.

FIGS. 9A to 9C are sectional side views schematically showing thestructure of a gate valve for a semiconductor processing systemaccording to a fourth embodiment of the present invention. The gatevalve 90 according to this embodiment has an arrangement in which, ascompared with the gate valve 20 according to the first embodiment, acompression spring is used in place of the tension spring for applying aresistant force against rotation of a swing frame 34, and therelationship between the bend and stretch movement of the linkmechanisms 36 and the opening and closing operation of the openingportion 14 are reversed.

More specifically, in the gate valve 90 according to this embodiment,the sidewall of a casing 16 on a side reverse to a load lock chamber 12side (the left side in FIGS. 9A to 9C) is provided with a guide 26disposed thereon, which extends vertically downward. A base frame 28 isattached to the guide 26 to move vertically along the guide 26. The baseframe 28 has a pair of arms 32 at the upper end, which extendhorizontally toward a load lock chamber 12, and have distal endspivotally supporting a swing frame 34.

A valve plug 24 is attached to the upper end of the swing frame 34. Theswing frame 34 is connected to the base frame 28 near the lower end by apair of link mechanisms 36. Each of the link mechanisms 36 can bend andstretch while flexing an intermediate portion. More specifically, eachof the link mechanisms 36 includes first and second levers 42 and 44,which are pivotally connected to the base frame 28 and the swing frame34, respectively. The first and second levers 42 and 44 are pivotallyconnected to each other by a mediation member 38.

The swing frame 34 is also connected to the base frame 28 by acompression spring 49 at the lower end. An air actuator 52 is fixed to acasing 16 between the base frame 28 and the swing frame 34. The airactuator 52 has a rod 54, which extends downward and verticallyreciprocates in the space between the base frame 28 and the swing frame34. The lower end of the rod 54 is connected to the mediation member 38of the link mechanisms 36.

A pair of first stoppers 56 are disposed at the upper end of the guide26, for defining the movement limit of the base frame 28 along the guide26 on the valve seat 22 side. The movement limit of the mediation member38 on the valve seat 22 side is defined by one end limit of the strokeof the reciprocation rod 54 of the air actuator 52.

In the gate valve 90, the swing frame 34 is provided with acounterclockwise biasing force by the compression spring 49 in FIGS. 9Ato 9C. When the opening portion 14 is opened (see FIG. 9A), the rod 54of the air actuator 52 is extended the most, and the link mechanism 36stretches the most. Consequently, the swing frame 34 is not in avertical state, but in a state where it has slightly rotatedcounterclockwise, and inclines in the casing 16. On the other hand, whenthe opening portion 14 is closed (see FIG. 9C), the rod 54 of the airactuator 52 is withdrawn the most, and the link mechanism 36 bends.Consequently, the swing frame 34 rotates clockwise against the biasingforce of the compression spring 49, so that the valve plug 24 seatsitself on the valve seat 22.

Although there are several differences other than the matters describedabove, the operation principle of the gate valve 90 is basically thesame as that of the gate valve 20. Accordingly, also in the gate valve90, the valve plug 24 is isolated from the driving section, and does notcome into contact with any portion other than the valve seat 22. As aresult, particles are prevented from being generated near the valve seat22 and the valve plug 24, so that the interior of a load lock chamber 12is unlikely to be contaminated with particles.

Note that the embodiments described above employ the air actuator 52 asa driving mechanism, but they may employ an alternative driving member,such as a hydraulically-operated cylinder. The embodiments describedabove employ a spring as a biasing member for applying a resistant forceagainst rotation of the swing frame 34, but they may employ analternative resilient member, such as rubber. Furthermore, theembodiments described above employ the valve seat 22 whose first sealsurface 22 a is vertical, but the present invention may be applied to acase where the first seal surface 22 a inclines relative to a verticalplane. In this case, the distance between the axial point of the swingframe 34 and the valve plug 24, and the inclining amount of the sealsurface 24 a of the valve plug 24 are appropriately adjusted.

The present invention is not limited by the embodiments described above,but can be practiced in various embodiments without departing from thespirit and scope of the invention. The features of the embodimentsdescribed above can be arbitrarily combined with each other in practice,thereby obtaining combined effects.

What is claimed is:
 1. A gate valve for a semiconductor processingsystem, comprising: a base frame configured movable in a first directionto move toward and away from a valve seat, which surrounds an openingportion and has a first seal surface facing a first reference plane; afirst stopper configured to define a movement limit of the base frame onthe valve seat side; a swing frame attached to the base frame, andconfigured rotatable on a second reference plane perpendicular to thefirst reference plane; a valve plug attached to the swing frame, andhaving a second seal surface to engage with the first seal surfacethereby to close the opening portion; a link mechanism connecting theswing frame to the base frame, and configured to bend and stretch whileflexing an intermediate portion; a driving mechanism connected to theintermediate portion, and configured to move the intermediate portion inthe first direction; and a biasing member configured to apply aresistant force against rotation of the swing frame relative to the baseframe, wherein, it is preset that, when the opening portion is closed,the intermediate portion is moved by the driving mechanism toward thevalve seat to first cause the base frame to move until the base framecomes into contact with the first stopper, and then cause the linkmechanism to bend or stretch thereby to rotate the swing frame, suchthat the valve plug seats itself on the valve seat, and the first andsecond seal surfaces engage with each other.
 2. The valve according toclaim 1, further comprising a guide fixed relative to the valve seat,wherein the base frame moves along the guide.
 3. The valve according toclaim 1, further comprising a damper disposed between the base frame andthe swing frame to absorb an impact caused when the swing frame rotatesrelative to the base frame by an action of the biasing member.
 4. Thevalve according to claim 1, wherein the driving mechanism comprises areciprocation rod connected to the intermediate portion.
 5. The valveaccording to claim 4, wherein the reciprocation rod penetrates a slithole formed in the intermediate portion, and the reciprocation rod ismovable relative to the intermediate portion in a range allowed by theslit hole.
 6. The valve according to claim 4, wherein the reciprocationrod is connected to the intermediate portion by a position adjustingmechanism, such that a connecting position of the reciprocation rodrelative to the intermediate portion is adjustable by the positionadjusting mechanism.
 7. The valve according to claim 4, wherein one endlimit of a stroke of the reciprocation rod is set to correspond to abend-and-stretch state of the link mechanism formed when the valve plugseats itself on the valve seat.
 8. The valve according to claim 1,further comprising a second stopper configured to define a movementlimit of the intermediate portion on the valve seat side to correspondto a bend-and-stretch state of the link mechanism formed when the valveplug seats itself on the valve seat.
 9. The valve according to claim 8,wherein the second stopper is fixed to the base frame.
 10. The valveaccording to claim 1, wherein the biasing member connects the swingframe to the base frame.
 11. The valve according to claim 1, wherein thelink mechanism comprises first and second levers connected to the baseframe and the swing frame, respectively, to be pivotable on the secondreference plane, and the intermediate portion connects the first andsecond levers to be pivotable to each other on the second referenceplane.
 12. The valve according to claim 1, wherein the first directionis substantially parallel to the first reference plane.
 13. The valveaccording to claim 1, wherein the valve plug and the link mechanism areconnected to the swing frame at first and second positions,respectively, sandwiching a position at which the swing frame isattached to the base frame.
 14. The valve according to claim 1, whereinthe opening portion is formed in a sidewall of an airtight chamber, inwhich a target substrate is accommodated, and the opening portion isformed to allow the target substrate to pass therethrough.
 15. The valveaccording to claim 14, wherein the valve seat and the valve plug arearranged to isolate a vacuum atmosphere inside the airtight chamber froman atmospheric environment outside the airtight chamber.
 16. A gatevalve for a semiconductor processing system, comprising: a base frameconfigured movable in a first direction to move toward and away from avalve seat, which surrounds an opening portion and has a first sealsurface facing a first reference plane; a first stopper configured todefine a movement limit of the base frame on the valve seat side; aswing frame attached to the base frame, and configured rotatable on asecond reference plane perpendicular to the first reference plane; avalve plug attached to the swing frame, and having a second seal surfaceto engage with the first seal surface thereby to close the openingportion; a link mechanism connecting the swing frame to the base frame,and configured to bend and stretch while flexing an intermediateportion, the link mechanism comprising first and second levers connectedto the base frame and the swing frame, respectively, to be pivotable onthe second reference plane, the intermediate portion connecting thefirst and second levers to be pivotable to each other on the secondreference plane; a driving mechanism comprising a reciprocation rodconnected to the intermediate portion, and configured to move theintermediate portion in the first direction; and a biasing memberconnecting the swing frame to the base frame, and configured to apply aresistant force against rotation of the swing frame relative to the baseframe, wherein, it is preset that, when the opening portion is closed,the intermediate portion is moved by the driving mechanism toward thevalve seat to first cause the base frame to move until the base framecomes into contact with the first stopper, and then cause the linkmechanism to bend or stretch thereby to rotate the swing frame, suchthat the valve plug seats itself on the valve seat, and the first andsecond seal surfaces engage with each other.